The invention relates generally to paper envelope (or similar package) closure means, and more particularly to such closure means in reusable form.
A very large number of paper envelopes are used each day in the conveyance of written and printed materials and the like from place-to-place through the world's postal service and otherwise. Many of these are sealed by a gum or cementing agent and are not intended to be reusable once they have been opened at their destinations, however, reusable envelopes in large numbers are in such daily uses as "inter-office" envelopes in the familiar office environment. It is in connection with that and other reusable envelope and package applications that the invention is of most interest and value.
In the prior art, various closure expedients are known. Among the prior art closures there are a number of reusable envelope closures such as the "string and buttons" type; the clasp on an envelope body bent flat after penetrating an opening in the envelope flap; and, more recently, Velcro (a trade name) patches on the envelope body and flap. Each of these prior art devices generally serves the general purpose of reusable envelope closure, but each presents its own disadvantage.
In a medium or large scale office operation, time is a factor to be considered. The "string and button" closure device is relatively inexpensive and provides a large number of reuse cycles but the opening and closing operations are relatively slow. The bendable clasp may afford somewhat faster opening and closing but fewer reuse cycles before breaking or excessive deformation of the clasp occurs.
In an apparent attempt to reduce opening and closing times, the Velcro patch device has been offered. A relatively large number of opening and closing cycles are provided, however, the Velcro patch device tends to make the envelope quite thick at its location, this causing a space problem as new envelopes are packed for shipment. That is, fewer envelopes can be stacked in a given package than for envelopes of the string and buttons or deformable metal clasp types. Although the mating Velcro patches provide rapid opening and closing, they are relatively expensive.
The manner in which the invention improves upon the prior art to provide a novel and highly advantageous reuse closure for an envelope or similar package.